In accordance with progress in the medical technology, surgical treatment has been available for diverse spots inside a living body. For example, there is a known symptom such as mitral valve insufficiency caused due to a rheumatic disease or the like disrupting opening and closing of a valve cusp in the heart. As surgical treatment for treating such a symptom, there is a known technique called mitral valve plasty (MVP).
The structure of the heart and the MVP will be described below in detail.
The heart has the atriums and the ventricles on the right and left, in which the mitral valve, the tricuspid valve, the aortic valve, and the pulmonary arterial valve cause blood to flow in a predetermined direction and prevent the blood from flowing backward.
FIGS. 1A and 1B are schematic views of a heart 300 of a human being. For example, a mitral valve 310 is formed between a left atrium 302 and a left ventricle 304, and two valve cusps 210 protrude from the left atrium 302 toward the left ventricle 304. When the left atrium 302 contracts, the valve cusps 210 are open and a blood flow heads for the left ventricle 304. In addition, when the left ventricle 304 contracts, the valve cusps 210 are closed and the blood flow is prevented from flowing backward to the left atrium 302. Accordingly, the blood flow unilaterally heads for an aorta 320 from the left ventricle 304. A tricuspid valve 312, an aortic valve 314, and a pulmonary arterial valve 316 are respectively configured with three sets of valve cusps 210, thereby causing blood flows to respectively and unilaterally head for a right ventricle 308 from a right atrium 306, for the aorta 320 from the left ventricle 304, and for a pulmonary vein 322 from the right ventricle 308.
A normal valve cusp 210 is joined to a papillary muscle 212 positioned in front (on downstream side) of the valve cusp 210 in a blood flow direction, by tendons 214. In FIGS. 1A and 1B, in regard to the mitral valve 310 and the tricuspid valve 312, the papillary muscles 212 and the tendons 214 are illustrated. In regard to the aortic valve 314 and the pulmonary arterial valve 316, illustration thereof is omitted. The valve cusps 210 are joined to the papillary muscles 212 by the tendons 214, thereby being able to maintain a state of protruding forward (to downstream side) in the blood flow direction. When being closed, while maintaining a state where the valve cusps 210 protrude forward (to downstream side), the valve cusps 210 adhere to each other, thereby closing a cardiac valve. When the cardiac valve is closed, the papillary muscles 212 contract and tensile forces of the tendons 214 increase. Accordingly, against the pressure of the blood flow flowing backward, the protruding state of the valve cusps 210 is maintained and the valve cusps 210 have no chance to be inverted in a backward direction.
However, for example, regarding a case of the mitral valve 310, there is a symptom such as mitral valve insufficiency caused due to a rheumatic disease, tendon rupture, or the like disrupting opening and closing of the valve cusps 210. In a case of such a symptom, the tendons 214 joining the valve cusps 210 of the mitral valve 310 and the papillary muscles 212 are stretched or broken. Accordingly, even if the papillary muscles 212 contract, the valve cusps 210 are not sufficiently closed, or the valve cusps 210 are inverted toward the left atrium 302. Similarly, in regard to the aortic valve 314, the tricuspid valve 312, and the pulmonary arterial valve 316 as well, valvular insufficiency disrupting opening and closing of the valve cusps 210 has been reported.
In surgical treatment for such valvular insufficiency of the cardiac valve, a procedure (valvoplasty) of joining the valve cusps 210 and the papillary muscles 212 together is performed by using string-like artificial tendons which are artificially produced so as to copy the tendons 214. As described above, the procedure related to the mitral valve 310 is called the mitral valve plasty (MVP). The MVP is surgical treatment performed with respect to such a symptom while aiming at normalizing the operation of the valve cusps 210 by joining the valve cusps 210 and the papillary muscles 212 with the artificial tendons.
PTL 1 discloses an auxiliary device that is an instrument used in the mitral valve plasty and includes a papillary muscle contact portion which is brought into contact with a portion of a papillary muscle stitched with an artificial tendon, and a hook portion which hooks a side of the artificial tendon stitching a valve cusp. The hook portion is formed on a tip side of a rod-shaped holding portion. The papillary muscle contact portion at a distal tip of the auxiliary device, and the hook portion are provided so as to be separated from each other by a predetermined size. While the artificial tendon stitching the papillary muscle is pressed by the papillary muscle contact portion, when both ends of the artificial tendon are tied together on the hook portion, the artificial tendon can have a length matching the predetermined size. Accordingly, the papillary muscle and the valve cusp can be joined together with the artificial tendon having a desired length. In addition, PTL 1 discloses that in order to join the artificial tendon with a desired length, the auxiliary device corresponding to the length of the artificial tendon to be reconstructed is selected, and a trial corresponding to the desired length is attempted.